Vacuum pump



FIG. 1 is a perspective view from the top front left side;

FIG. 2 is a front view;

FIG. 3 is a rear view;

FIG. 4 is a top view;

FIG. 5 is a bottom view;

FIG. 6 is a view from the right side; and,

FIG. 7 is a view from the left side. 

The ornamental design for a vacuum pump, as shown. 